Hydraulic-brake solution



Patented Apr. 1-7, 1928.

UNITE WILLIAM G. CALKINS,

TION, F HIGHLAND PARK, MI

No Drawing.

This invention relates to o STATES PATENT OFFICE.

0F DETROIT, MICHIGAN, ASSIGNOR TO CHRYSLER COICPORA- CHIGAN, A CORPORATION OF DELAWARE.

HYDRAULIC-BRAKE soLU'rIoN.

Application filed October 9, 1926. Serial No. 140,686.

a low vapor pressure. high boiling point solution and more particularly to a solution adapted for use in a closed hydraulic system such as is com- 5 monly tem.

In closed hydraul type which operate used in a closed hydraulic brake sysic brake systems of the on automoblle vehicles,

it is diflicult to maintain a constant pressure within the system to vaporization solution used. Cert tem may be exposed to heated parts of the vehicle, so as to absorb heat therefrom, as for example, one of brake operating mechanism may be adjacent the muliler or motor. used on frictional heat causes vaporization of the ordinary solution, creating a pressure in which locks the brakes. pheric pressure cause changes in the pres sure when aused. It is therefore an invention to provide a solution having a high boiling point.

Certain hydraulic operating parts made of steel, their connecting lines usually are made of copPertubing, and where flexibility is required, rub ber hose is commonly used. The operating parts require lubrication and to lubricate these parts by the solution used in the system, it is necessary at all temperatures, and condensatlon of the due ain portions of the systhe lines leading to the This and other heat, from the brake drum,

the entire system Changes in atmoslow boiling point solution is important object of this to provide a solution which has no corrosive effect on other parts of the system such Light mineral oils as rubber and copper.

are objectionable in that they attack the rubber and cause deterioration thereof.

Another object of this invention is to provide a solution having lubricating qualities which will have no corrosive effect on the parts of the system.

but due to its viscosity when used without dilution, it is not desirable for exceedingly low temperatures.

viscosity and as bef It therefore becomes necessary to dilute the castor oil with a liquid of less ore mentioned one hav- -prophyl, iso prophyl, et cetera, have a brake'systems have their mg approximately ing a high boiling point and no effect on the parts of the system.

Any of the higher alcohols or their deriva tives, such as butyl, iso butyl, amyl, iso amyl,

boiling point at atmospheric pressure higher than 80 centigrade. The boiling points of these alcohols range from 82 centigrade, iso propyl, t0 137.8 centigrade, normal amyl.

Normal butyl alcohol, CH (CH (LI-L0H, has a boiling point of 117 centigrade and when used to dilute the castor oil a noncorrosive solution is produced which has lubricating qualities and vaporizes only at a temperature above unusual conditions.

\Vhile amyl alcohol, CH (GH CH OH,

has aboiling point of 137.8 centigrade it causes the sulphur in the rubber connections of the system to attack the copper tubing forming a black copper sulphide corrosion within the system. Through a series of tests butyl alcohol has been found most desirable as it has less action on the parts of the system, its boiling point is sufficiently high to prevent vaporization under extraordinary condition, and it is a more commercial product.

It has been found that a solution consistof castor oil and of one of these higher alcohols, particularly butyl alcohol, makes a desirable solution. \Vhere butyl alcohol is used, the solution has a. boiling point of 117 centigrade 01 2 2 Fahrenheit as compared to 76 centigrade, 170 Fahrenheit,when ordinary denatured alcohol is used; the latter being undesirable.

It is to be understood that while butyl a1- cohol has been found to be" the most satisfactory to meet the requirements for a solution used in a sytsem of the class described,

other derivatives of the higher alcohols may .be used when the parts of the system are not 2. A hydraulic solution composed of approximately iifty percent castor oil and a proximately fifty percent butyl alcohol.

composed of cas alcohol having a C. at atmospheric 3. A hydraulic solution 5 tor oil and :1- monohydric boiling point above 80 pressure.

4. A hydraulic solution com proximately fifty percent casto posed of apr oi series having a boiling point not less than 117 C. at atmospheric pressure WILLIAM G. CALKINS. 

